We request funds to purchase an ACAS 570 interactive laser cytometer and data analysis workstation by Meridian Instruments to enhance the progress of PHS-funded research conducted at the University of Rochester, School of Medicine and Dentistry, and to benefit the University's NIH-supported trainees. Dr. James E. Melvin, the Principal Investigator and Facility Director, routinely uses dual wavelength detection of fluorescent ion-sensitive dyes ([Ca2+] or Ph) to study stimulus-secretion coupling in exocrine glands. Many of these studies are in collaboration with Dr. Ted Begenisich, the Co-Principal Investigator and Facility Co-Director. Dr. Begenisich examines the chemical and molecular properties of ion channels using a combination of patch clamp and molecular biological techniques. A Technical Advisory Committee has been established to advise users on developing experimental protocols and to develop programs for expanding the data acquisition and analysis capabilities of the ACAS 570. The members of the Technical Advisory Committee include, besides Drs. Melvin and Begenisich, Dr. Peter Keng, Director of the Flow Cytometry and Centrifugal Elutriation Facilities, Dr. James Leary, Director of the Cell Analysis and Sorting Laboratory, and Dr. Shey-Shing Sheu, an expert in dual wavelength fluorescent ratio imaging. The ACAS 570 laser cytometer is the only commercially available dual wavelength fluorescence imaging system which will sort and photobleach live, adherent cells. The questions being addressed by PHS-funded investigators in this grant proposal require: i) selecting and cloning cells based in fluorescence imaging measurements of adherent cells, ii) fluorescence redistribution after photobleaching (FRAP), iii) confocal imaging of intracellular structures, ion distribution, and cell-cell associations, and iv) spatial/temporal fluorescence analysis of live adherent cells. The instrument will be used and administered by a multidisciplinary user group composed of 20 investigators. The Organizational Plan includes an Internal Advisory Committee, a Facility Director and Co-Director, a Technical Advisory Committee, and a Student Training Committee. In addition, a plan for the management of the ACAS 570 Shared Resource Facility has been proposed, space and funds for renovation of this space have been identified, and an Institutional commitment of stable long-term support has been provided.